Method of recording information on optical disks at a recording density proportional to the actual information volume and disk nominal capacity

ABSTRACT

A method is designed for recording contents information along a track of an optical disk of a writeable type. A volume detection step is carried out for detecting an actual volume of the contents information to be recorded into the optical disk. A capacity detection step is carried out for detecting a nominal capacity of the optical disk, which indicates a rated volume of information to be recorded at maximum. A density determination step is carried out for determining a recording density of the contents information based on the detected actual volume and the detected nominal capacity. A recording step is carried out for recording the contents information into the optical disk at the determined recording density such that the actual volume of the contents information can fit into the nominal capacity of the optical disk.

RELATED APPLICATION DATA

This is a divisional of application Ser. No. 10/207,302, filed Jul. 29,2002, now U.S. Pat. No. 7,046,597 which is based on Japanese PatentApplication No. 2001-230392, filed Jul. 30, 2001.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an optical disk recording method andoptical disk recording apparatus in which contents information isrecorded in optical disks such as a compact disk-recordable (CD-R) andCD-rewritable (CD-RW).

2. Discussion of the Related Art

In a recordable optical disk conforming to CD standard such as CD-R, aguide groove called a pregroove is formed beforehand along a track in adisk manufacturing process. The pregroove wobbles (meanders), and awobbling frequency thereof is detected and subjected to frequencymodulation (FM) with absolute time information called Absolute Time inPregroove (ATIP).

During the recording of contents information into the optical disk inwhich the pregroove is formed, a wobbling signal is extracted from aphoto signal of a light reflected back from the optical disk, thewobbling signal is FM-demodulated to decode ATIP information, and anabsolute position along the track on the disk is detected by the decodedATIP information. Moreover, the detected absolute position informationis used to record the contents information in the optical disk.

Additionally, types of optical disks having different recordingcapacities have been distributed. For example, with regard to CD-R, adisk having a recording capacity of 650 MB (megabyte) and another diskhaving a recording capacity of 540 MB have been marketed. The CD-Rhaving the nominal recording capacity of 650 MB and the CD-R having thenominal recording capacity of 540 MB have the same physical length ofthe recordable track, but these two types of disks are different fromeach other in the operating speed regulated according to the progressionof the absolute time information of the ATIP information extracted fromthe disks. That is, the track length for use in recording the absolutetime information of the ATIP information differs between these two typesof disks. For example, the track length for use in storing the absolutetime information of ten minutes in the optical disk of 540 MB is largerthan that of the optical disk of 650 MB. Therefore, the disks aredifferent from each other in the recording density of the absolute timeinformation. As a result, the recording capacity differs between thesetwo types of optical disks. That is, during recording at a standardoperation speed, the CD-R of 650 MB adopts a linear velocity of 1.2 m/s,the CD-R of 540 MB adopts a linear velocity of 1.4 m/s, and these linearvelocities are referred to as rated linear velocities of the respectivedisks in the standard of the optical disk. Additionally, the “linearvelocity” in the standard actually has the same meaning as the recordingdensity. For example, the CD-R of 650 MB is different from the CD-R of540 MB in the capacity to be recorded per unit track length. Namely, theCD-R of 650 MB is different from the CD-R of 540 MB in the recordingdensity. The density of the CD-R of 650 MB is larger than that of theCD-R of 540 MB. The recording density obtained when the linear velocityis set to 1.2 m/s or 1.4 m/s during recording at the standard operationspeed bears a reciprocal relationship to the linear velocity of 1.2 m/sor 1.4 m/s in the above-described standard. Therefore, the term “linearvelocity” will be used hereinafter for representing the recordingdensity. The value 1.4 m/s denotes an information recording pitch at thestandard operation speed and is therefore used for indicating therecording density in recording the information at the linear velocity of1.4 m/s. Similarly, the value 1.2 m/s denotes an information recordingpitch at the standard operation speed and is used for indicating therecording density in recording the information at the linear velocity of1.2 m/s. Theoretically, the greater the value of the linear velocity,the smaller the recording density, because the linear velocity isinversely proportional to the recording density.

CD-R disks having various recording capacities have been manufacturedand marketed, with the user having to spend some effort in selecting aCD-R which has the recording capacity to accept the data amount to berecorded. For example, a CD-R of 650 MB may be selected in order torecord music data for 74 minutes (CD-DA form: CD digital audio). A CD-Rof 700 MB may be selected to record music data for 80 minutes, and aCD-R of 540 MB may be selected to record music data for 63 minutes orless. The disk-selection process is troublesome, and further, the userneeds to prepare various types of CD-R disks beforehand. Moreover, whena CD-R having an appropriate recording capacity is not available, timeand effort must be spent in locating and purchasing a CD-R that has theappropriate capacity. Furthermore, in general, as the recording lineardensity becomes smaller, it is possible to record the recordinginformation with an improved quality level. However, in conventionaloperation, when data of 550 MB is recorded in a CD-R of 650 MB, arecording area of 100 MB is left unused, and a technique of effectivelyusing such an unused extra area has not been proposed.

SUMMARY OF THE INVENTION

The present invention has been developed in consideration of theabove-described circumstances, and an object thereof is to provide anoptical disk recording method and optical disk recording apparatus inwhich information can be preferably recorded in accordance with acapacity of data to be recorded and a capacity recordable in the opticaldisk.

To solve the above described problem, according to the presentinvention, there is provided a method of recording contents informationalong a track of an optical disk of a writeable type. The inventivemethod comprises a volume detection step of detecting an actual volumeof the contents information to be recorded into the optical disk, acapacity detection step of detecting a nominal capacity of the opticaldisk, which indicates a rated volume of information to be recorded atmaximum, a density determination step of determining a recording densityof the contents information based on the detected actual volume and thedetected nominal capacity, and a recording step of recording thecontents information into the optical disk at the determined recordingdensity such that the actual volume of the contents information can fitinto the nominal capacity of the optical disk.

According to the inventive method, the recording density can be changedbased on the actual information volume to be recorded and the nominalinformation volume recordable in the optical disk (nominal recordingcapacity), and the information is recorded at the determined linearvelocity such that the information can preferably be recorded inaccordance with a relation between the actual information volume to berecorded and the nominal recordable information volume. For example,when the actual information volume to be recorded is small, therecording density is decreased, and thereby the recording with a higherquality level is possible. On the other hand, when the actualinformation volume to be recorded is large, the recording density isincreased, and thereby data having a volume larger than the nominalrecordable capacity can be recorded.

Moreover, according to another aspect of the present invention, there isprovided a method of recording contents information along a track of anoptical disk which is prerecorded with index information indicatingprogression of position or time along the track at a predeterminedrecording density. The inventive method comprises the steps ofmodulating an optical beam according to the contents information inresponse to a reference clock signal, irradiating the modulated opticalbeam along the track of the optical disk while rotating the optical diskat a variable rotational velocity so as to optically write the contentsinformation into the optical disk, and adjusting either of a frequencyof the reference clock signal and the rotational velocity of the opticaldisk so as to record the contents information at a recording densitydifferent from the predetermined recording density of the indexinformation.

According to the inventive method, the rotational velocity of theoptical disk during the recording and/or the frequency for use inmodulating the information to be recorded is controlled, hence theinformation can be recorded with the recording density other than thepredetermined default recording density set in the optical disk. Forexample, when the actual information volume to be recorded is small, therecording density is decreased, and thereby recording with a higherquality level is possible. On the other hand, when the actualinformation volume to be recorded is large, the recording density isincreased, and thereby data having a volume larger than the nominalrecordable information capacity can be recorded.

Furthermore, according to a further aspect of the present invention,there is provided a method of recording a volume of contents informationalong a track of an optical disk which is prerecorded with indexinformation indicating progression of position or time along the trackat a predetermined recording density to rate a capacity of the opticaldisk. The inventive method comprises the steps of determining arecording density based on an actual volume of the contents informationto be recorded into the optical disk and the rated capacity of theoptical disk, modulating an optical beam according to the contentsinformation in response to a reference clock signal, irradiating themodulated optical beam along the track while rotating the optical diskat a variable rotation velocity so as to optically record the contentsinformation, and adjusting either of a frequency of the reference clocksignal and the rotation velocity of the optical disk when the determinedrecording density differs from the predetermined recording density forrecording the contents information at the determined recording densitysuch that the actual volume of the contents information can becompressed or expanded into the rated capacity of the optical disk.

According to the inventive method, the rotational velocity of theoptical disk and/or the frequency for use in modulating the informationto be recorded is controlled based on the actual information volume tobe recorded and the nominal information volume recordable in the opticaldisk, hence the recording density can be changed freely without stickingto the predetermined default recording density set in the optical disk.The information is recorded at the determined linear velocity such thatoptimal recording is possible in accordance with the relationshipbetween the actual information volume to be recorded and the nominalrecordable information volume. For example, when the actual informationvolume to be recorded is small, the recording density is decreased, andthereby recording with a higher quality level is possible. On the otherhand, when the actual information volume to be recorded is large, therecording density is increased, and thereby data having a capacitylarger than the nominal recordable information capacity can be recorded.

Additionally, according to the present invention, there is provided anapparatus for recording contents information into a track of an opticaldisk of a writeable type. The inventive apparatus comprises a volumedetecting section that detects an actual volume of the contentsinformation to be recorded into the optical disk, a capacity detectingsection that detects a nominal capacity of the optical disk, whichindicates a rated volume of information to be recorded at maximum, aclock setting section that sets a frequency of a reference clock signalaccording to the detected actual volume of the contents information andthe detected nominal capacity of the optical disk, a modulating sectionthat modulates an optical beam according to the contents information inresponse to the set frequency of the reference clock signal, and anirradiating section that irradiates the modulated optical beam onto thetrack so as to optically write the contents information into the opticaldisk such that the actual volume of the contents information can befilled into the nominal capacity of the optical disk.

According to the constitution, the frequency of the reference clocksignal for use in modulating the contents information to be recorded canbe changed based on the actual information volume to be recorded and thenominal information volume recordable in the optical disk. When thefrequency of the reference clock signal for use in the modulation ischanged in this manner, the recording density can be accordinglychanged, and the information can be recorded at the optimum linearvelocity so as to perform optimal recording in accordance with therelationship between the actual information volume to be recorded andthe nominal recordable information volume.

Moreover, according to the present invention, there is provided anapparatus for recording contents information into a track of an opticaldisk of a writeable type. The inventive apparatus comprises a volumedetecting section that detects an actual volume of the contentsinformation to be recorded into the optical disk, a capacity detectingsection that detects a nominal capacity of the optical disk, whichindicates a rated volume of information to be recorded at maximum, arotation control section that rotates the optical disk at an angularvelocity controlled according to the detected actual volume of thecontents information and the detected nominal capacity of the opticaldisk, a modulating section that modulates an optical beam according tothe contents information, and an irradiating section that irradiates themodulated optical beam onto the track so as to optically write thecontents information into the optical disk which is rotated at thecontrolled angular velocity such that the actual volume of the contentsinformation can be filled into the nominal capacity of the optical disk.

According to the constitution, the angular driving speed of the opticaldisk as a recording object can be changed based on the actualinformation volume to be recorded and the nominal information volumerecordable in the optical disk. When the angular driving speed of theoptical disk is changed in this manner, the recording density can bechanged accordingly, and the information can be recorded at thecorresponding linear velocity so as to perform optimal recording inaccordance with the relation between the actual information volume to berecorded and the nominal recordable information volume.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram showing a principle of an optical disk recordingmethod according to one embodiment of the present invention.

FIG. 2 is another diagram showing a principle of an optical diskrecording method according to one embodiment of the present invention.

FIG. 3 is an additional diagram showing a principle of an optical diskrecording method according to one embodiment of the present invention.

FIG. 4 is an additional diagram showing a principle of an optical diskrecording method according to one embodiment of the present invention.

FIG. 5 is an explanatory diagram showing an effect achieved by theoptical disk recording method according to one embodiment of the presentinvention, and illustrates an eye pattern obtained from a reproductionsignal during recording at different linear velocities.

FIG. 6 is an explanatory diagram showing the effect achieved by theoptical disk recording method according to an embodiment of the presentinvention.

FIG. 7 is a block diagram showing the constitution of an optical diskrecording apparatus designed for carrying out an optical disk recordingmethod.

FIG. 8 is a block diagram showing the constitution of a modulation clockgeneration circuit as an element of the optical disk recordingapparatus.

FIG. 9 is an explanatory table showing a dividing ratio set in a dividerof the modulation clock generation circuit in order to carry out anoptical disk recording method.

FIG. 10 is an explanatory diagram showing contents of a table stored ina ROM of a control unit in a modification example of the optical diskrecording apparatus.

FIG. 11 is a diagram showing the constitution of a spindle controller ofan optical disk recording apparatus designed for carrying out an opticaldisk recording method.

DETAILED DESCRIPTION OF THE INVENTION

Embodiments of the present invention will be described hereinafter withreference to the drawings.

A. Data Recording Method for Optical Disk

FIGS. 1 to 4 are explanatory diagrams illustrating a principle of amethod of recording data in an optical disk (hereinafter referred to asCD-R) according to one embodiment of the present invention. The methodof recording data with respect to the optical disk according to thepresent embodiment will be described with reference to the drawings.

First, a basic principle of the recording method according to thepresent embodiment will be described. As shown in FIG. 1, for CD-R, aplurality of types of disks having the same track length TR (tracklength of a region in which contents information is recorded) and havingdifferent recording capacities are available, such as a disk with arecording capacity of 650 MB (rated linear velocity of 1.2 m/s) and adisk with a recording capacity of 540 MB (rated linear velocity of 1.4m/s).

To record the information in the CD-R, the information has heretoforebeen written in accordance with the rated linear velocity of the setCD-R. In the recording method according to the present embodiment,however, in accordance with the recording data capacity (hereinafterreferred to as a disk capacity, or nominal capacity N) of the CD-R setin an optical disk recording apparatus, and a data amount to be recorded(hereinafter referred to as a recording data amount, or actual volumeM), the information is recorded at an optimal recording linear velocitywithout being limited to the rated linear velocity of the CD-R.

The recording method based on the above-described basic principle willbe described hereinafter in terms of three cases having the recordingdata amounts M of about 650 MB (Case 1), about 670 MB (Case 2), andabout 540 MB (Case 3) for an object CD-R (upper optical disk of FIG. 1)which is set in the optical disk recording apparatus and which has thedisk capacity N of about 650 MB (track length TR, rated linear velocity1.2 m/s).

(Case 1) Recording Data Amount M=650 MB

As shown in FIG. 2, in the case where the recording data amount M is 650MB, that is, the disk capacity N agrees with the recording data amountM, the recording is performed at the linear velocity identical to therated linear velocity (1.2 m/s) of the CD-R as the recording object. Asa result, a program area in which the contents data of the CD-R can berecorded is fully utilized (oblique lines in the drawing indicate arecorded area), and data of 650 MB is recorded. Thus, where, as in thepresent example, the disk capacity N agrees with the recording dataamount M, the recording is carried out at the rated linear velocity,which corresponds to the conventional method of recording data.

(Case 2) Recording Data Amount M=670 MB

Subsequently, when the recording data amount M is 670 MB, that is, therecording data amount M is larger than the disk capacity N, and the dataamount M exceeding the disk capacity N is recorded, during a so-called“over burn”, as shown in FIG. 3, the recording is performed at a linearvelocity of 1.2×650/670 (i.e., about 1.16 m/s), as opposed to the ratedlinear velocity (1.2 m/s) of the disk. As a result, the recording dataamount M (670 MB) can be recorded using all the program area (650 MB) ofthe CD-R. In contrast, in the conventional recording method using therated linear velocity, even when all of the program area of the CD-R isused, the data for 20 MB cannot be recorded. Thus, in the recordingmethod according to the present embodiment, when the information isrecorded at a linear velocity lower than the rated linear velocity asdescribed above, it is possible to record an amount of data (e.g., 670MB) that is larger than the disk capacity N. Therefore, generation of arecording error resulting from the over burn can be prevented, and theuser does not have to perform a laborious operation of replacing theCD-R with a disk having a larger capacity.

(Case 3) Recording Data Amount M=540 MB

Subsequently, when the recording data amount M is 540 MB, that is, therecording data amount M is smaller than the disk capacity N, as shown inFIG. 4, the recording is performed at a linear velocity or 1.2×650/550(i.e., about 1.4 m/s), as opposed to the rated linear velocity (1.2 m/s)of the disk. As a result, the data of 540 MB can be recorded using allthe program area (650 MB) of the CD-R. On the other hand, in theconventional recording method using the rated linear velocity, all thedata can be recorded using the region for 540 MB in the program area,but an unrecorded area for 110 MB remains. Of course, even when theunrecorded area for 110 MB remains, the data recorded in the CD-R can bereproduced without any problem. However, in the present embodiment, forthe following reason, when the recording data amount M is smaller thanthe disk capacity N, the information is recorded at a higher linearvelocity (lower recording density) than the rated linear velocity, whichallows for recording at a higher level of quality. In this way, when thedisk capacity includes an extra region, the extra region is used and therecording density is lowered, so that data having a higher reproductionquality, such as music data, can preferably be recorded.

To verify an influence of the reduced recording density on the recordingquality level, the present inventor has obtained an eye pattern of an RFsignal extracted from a reproduction signal during the recording at thelinear velocity set to 1.4 m/s, and another eye pattern extracted fromthe reproduction signal during the recording at the linear velocity setto 1.2 m/s in the same CD-R, and the obtained result is shown in FIG. 5.In the two eye patterns shown in the drawing, upon comparing the eyepatterns from pits of 3T (T is a reference clock) portions as a minimumpit length of the recording of the CD-R, it is apparent that anamplitude A 1.4 shown in the eye pattern obtained by the recording atthe linear velocity of 1.4 m/s is greater than an amplitude A 1.2 at thelinear velocity of 1.2 m/s. Moreover, the experimental results show thatthe amplitude of the 3T pit in the linear velocity of 1.4 m/s (smalldensity) increases in this manner, and amplitudes B 1.4 and B 1.2 oflong pits have little difference. That is, the long pit is hardlyinfluenced by the linear velocity, whereas the short pit is largelyinfluenced by the linear velocity. When the linear velocity is low, theamplitude further increases. Here, a pit signal which influences aprecision of signal detection is in a portion below an amplitude center,and the portion is naturally proportional to the size of the amplitude,and is enlarged when the linear velocity is low as described above.Moreover, it is seen from the drawing that the eye pattern of the linearvelocity of 1.4 m/s is represented more clearly than the eye pattern of1.2 ml/s. This shows that a jitter (standard deviation of a recordingpit length and recording land length from a standard length) obtains asmaller value (the high quality level) during the recording at 1.4 m/s,and for an actual measurement result of the jitter value, a resultobtained by the recording at the linear velocity of 1.4 m/s is superior.It is apparent from the results of the experiment that recording with ahigher quality level is possible by the reduction of the recordingdensity (i.e., recording at the higher linear velocity of 1.4 m/s ratherthan 1.2 m/s).

As indicated in the above-described experimental result, when therecording density is decreased, recording at a higher quality level ispossible for the following reason. In consideration of a relationbetween the 3T pit (minimum pit length) formed in the CD-R and a spotdiameter of a laser beam with which the CD-R is irradiated, as shown inthe upper part of FIG. 6, when the pit length of a pit P1 (shown by asolid line in the drawing) recorded at the linear velocity of 1.4 m/s issubstantially equal to a spot diameter R, it is seen that the pit lengthof a pit P2 (shown by a one-dot chain line in the drawing) recorded atthe linear velocity of 1.2 m/s is smaller than the spot diameter R. Sucha dimensional relationship between the pit length and the spot diameterR is caused by the above-described sizes of the amplitudes A 1.4 and A1.2. Moreover, as shown in the lower part of FIG. 6, with the long pit(e.g., 11T), the pit length of a pit P3 (shown by a solid line in thedrawing) recorded at the linear velocity of 1.4 m/s and that of a pit P4(shown by a one-dot chain line in the drawing) recorded at the linearvelocity of 1.2 m/s are greater than the spot diameter R. As a result,there is no substantial difference between the amplitudes B 1.2 and B1.4.

As described above, when the recording density is decreased (the linearvelocity is raised), recording with a higher quality level is apparentlyperformed. This is noticeable in the recording method according to thepresent embodiment. When the recording data amount M is smaller than thedisk capacity N as described above, that is, when there is an extra diskcapacity N, the extra region is used to record the information at alinear velocity that is higher than the rated linear velocity.

Thus, in the recording method according to the present embodiment, whenthe rated linear velocity of a CD-R 101 is L, a linear velocity LT forthe recording is obtained by the following equation, and the recordingis performed at a linear velocity of LT:LT=L×N/M

When the information is recorded at the set linear velocity, and whenthe recording data amount M is larger than the disk capacity N, therecording data can all be recorded in the CD-R. On the other hand, whenthe recording data amount M is smaller than the disk capacity N, theextra region of the disk capacity N is used, and the recording with ahigher quality level is possible. That is, according to the recordingmethod of the present embodiment, the information can be recorded at anoptimum linear velocity in accordance with the disk capacity N andrecording data amount M without being restricted by the rated linearvelocity of the disk.

Additionally, in the above equation, N/M is used instead of M/N, whichis recited in the claims. However, given the reciprocal relationshipbetween the linear velocity and the recording density, this means thatthe greater the value of the “linear velocity” (as used in thespecification), the smaller the value of the “recording density” (asrecited in the claims). Therefore, when, as in the claims, the recordingdensity is used as a unit instead of the “linear velocity”, the equationis represented by LT=L×M/N.

B. Optical Disk Recording Apparatus

The optical disk recording method according to the present embodimenthas been described above, and an optical disk recording apparatus forcarrying out the inventive optical disk recording method will bedescribed hereinafter.

First, FIG. 7 is a block diagram showing the constitution of an opticaldisk recording apparatus 100 according to one embodiment of the presentinvention, and the optical disk recording apparatus 100 is connected toa host computer (not shown) and used. As shown in the drawing, theoptical disk recording apparatus 100 includes a spindle motor 11,optical pickup 12, recording strategy circuit 13, EFM modulation unit(i.e., modulating section) 14, modulation clock generation circuit(i.e., clock setting section) 15, divider 16, wobble signal extractionunit 17, ATIP demodulation unit 18, spindle controller 19, control unit20, crystal oscillator 21, and changeover switch 22.

The spindle motor 11 is a motor for rotationally driving an optical disk(CD-R in the present embodiment) as an object in which data is recorded.The optical pickup (irradiating means or section) 12 has an opticalsystem including a laser diode, lens, mirror, and the like, and a returnlight receiving element. To record the data in the CD-R 101, the opticalpickup irradiates a track of the CD-R 101 with a laser beam, receives areturn light from the CD-R 101, and outputs an RF signal subjected to aneight-to-fourteen modulation (EFM) as a light receiving signal to thewobble signal extraction unit 17 via an RF amplifier (not shown).

The wobble signal extraction unit 17 extracts a wobble signal from theRF signal supplied from the optical pickup 12 via the RF amplifier andsubjected to the EFM, and outputs the extracted wobble signal to theATIP demodulation unit 18. As described above, a pregroove is formedalong the track in the CD-R 101. Moreover, the pregroove wobbles, andthe wobble signal extraction unit 17 extracts a wobbling signal WB as acomponent resulting from the wobbling from the RF signal supplied fromthe optical pickup 12.

The ATIP demodulation unit 18 demodulates the wobbling signal WBextracted by the wobble signal extraction unit 17, and extracts an ATIPsignal AP and bi-phase clock BC. The ATIP demodulation unit 18 outputsthe demodulated biphase clock BC to the spindle controller 19, andoutputs the demodulated ATIP signal AP to the changeover switch 22 andcontrol unit 20.

The spindle controller 19 uses the bi-phase clock BC supplied from theATIP demodulation unit 18, and a clock signal CK supplied from thecrystal oscillator 21 and having a predetermined frequency to drive thespindle motor 11. More specifically, the spindle controller 19 has aphase comparator and motor driver. The bi-phase clock BC is inputtedinto one input end of the phase comparator, and a signal obtained bydividing the clock signal CK at a predetermined dividing ratio isinputted into the other input end. As a result, an error signal isoutputted to the motor driver from the phase comparator in accordancewith a phase difference of both inputs, and the motor driver drives thespindle motor 11 in accordance with the error signal. When the spindlecontroller 19 drives the spindle motor 11 in this manner, the spindlemotor 11 can rotate the CD-R 101 so as to maintain a linear velocity ofthe track relative to the beam spot constant regardless of the recordingposition of the CDR 101. That is, a constant linear velocity (CLV)driving is possible.

When the information is recorded in the above-described CD-R of 650 MB(rated linear velocity of 1.2 m/s) with the standard operation speeddefined in the CD standard, the frequency of the wobbling signal WBextracted by the wobble signal extraction unit 17 is 22.05 kHz, and thebiphase clock BC and ATIP signal AP have a frequency of 6.3 kHz.Therefore, when the information is recorded in the CD-R 101 having therated linear velocity of 1.2 m/s with the standard operation speed, thespindle controller 19 carries out spindle servo so as to set thefrequency of the wobbling signal WB to 22.05 kHz, and the frequency ofthe bi-phase clock BC to 6.3 kHz. As a result, to perform the recordingat the standard operation speed, the spindle motor 11 is driven so thatthe recording is performed at a linear velocity of 1.2 m/s, that is, thelinear velocity agreeing with the rated linear velocity of the CD-R 101.Additionally, to perform the recording at higher operation speeds, suchas a double speed, and four-fold speed, the frequencies of the wobblingsignal WB, bi-phase clock BC, and ATIP signal AP have values double orfour times, respectively, the above-described numeric values.

During recording in a constant angular velocity (CAV) system, the ATIPsignal AP from the ATIP demodulation unit 18 is supplied to themodulation clock generation circuit 15 via the changeover switch 22, andis used in generating a clock signal for modulation in the EFMmodulation unit 14. On the other hand, during the recording in the CLVsystem, the changeover switch 22 is connected so that the clock signalCK from the crystal oscillator 21 is supplied to the modulation clockgeneration circuit 15.

The control unit (frequency setting means) 20 is constituted of acentral processing unit (CPU), read only memory (ROM), random accessmemory (RAM), and the like, and all components of the optical diskrecording apparatus 100 are controlled according to a program stored inthe ROM so that a recording processing is executed. In this case, inaddition to a control similar to a usual control of the general opticaldisk recording apparatus, the control unit 20 is constituted to performthe following characteristic control so that the recording is performedat an optimum linear velocity in accordance with the recording dataamount M and the disk capacity N.

The control unit 20 recognizes the recording position by the opticalpickup 12 based on the ATIP signal AP supplied from the ATIPdemodulation unit 18, reads out ATIP special information and the like,recognizes a maximum leadout start possible time (the last possiblestart position of the lead-out area in ATIP time code) of the CD-R 101indicated in the ATIP special information, and detects the disk capacityN as the data amount recordable in the CD-R 101 based on the recognizedmaximum lead-out start time. As described above, when the CD-R 101 is adisk having a rated linear velocity of 1.2 m/s, the CD-R 101 can bedetected to be a disk having a recording capacity of 650 MB from themaximum lead-out start possible time indicated in the ATIP specialinformation.

The control unit 20 supplies a control signal SB for setting thedividing ratio of the divider in the modulation clock generation circuit15 described later based on the detected recording capacity of the CD-R101 (hereinafter referred to as a disk capacity) and the actual volumeof the data to be recorded supplied from the host computer (hereinafterreferred to as the recording data amount). That is, the control unit 20derives the dividing ratio of the divider in the modulation clockgeneration circuit 15 based on the disk capacity of the CD-R 101 and therecording data amount, and outputs the control signal SB for setting thederived dividing ratio to the modulation clock generation circuit 15.

The modulation clock generation circuit 15 uses the control signal SBsupplied from the control unit 20 and the clock signal CK having apredetermined period supplied from the crystal oscillator 21, generatesa modulating clock signal MCK for use in the EFM modulation of therecording data in the EFM modulation unit 14, and outputs the signal tothe divider 16. The modulating clock signal MCK is divided into 1/K(fixed value) by the divider 16, and the divided modulating clock signalMCK′ is supplied to the EFM modulation unit 14 and used in the EFMmodulation of the recording data.

As shown in FIG. 8, the modulation clock generation circuit 15 has aphase comparator 150, voltage controlled oscillator (VCO) 151, anddivider 152.

A signal is inputted into one input end of the phase comparator 150 inaccordance with a connection state of the changeover switch 22. In thepresent embodiment, the changeover switch 22 is connected to a crystaloscillator 21 side during the recording in a CLV system, and thechangeover switch 22 is connected to the ATIP demodulation unit 18during the recording in a CAV system. Here, the recording in the CLVsystem is described as an example, and a clock signal CK′ obtained bydividing the clock signal CK supplied from the crystal oscillator 21with the predetermined dividing ratio is inputted into one input end ofthe phase comparator 150. For example, when the recording is performedat the standard operation speed, the frequency of the clock signal CK′supplied to one input end of the phase comparator 150 is 6.3 kHz. Thefrequency is 12.6 kHz at the double operation speed, and 25.2 kHz at thefour-fold operation speed, and the frequency also increases inproportion to the multiple operation speed.

A clock signal CN outputted from the divider 152 is supplied to theother input end of the phase comparator 150. The dividing ratio of thedivider 152 can optionally be varied, and the dividing ratio (1/B) isset in accordance with the control signal SB supplied from theabove-described control unit 20 (see FIG. 7). Therefore, the clocksignal CN obtained by dividing the modulating clock signal MCK outputtedfrom the voltage controlled oscillator 151 at (1/B) is supplied to theother input end of the phase comparator 150. The phase comparator 150outputs a phase error signal IG of the clock signal CN and clock signalCK′ (6.3 kHz at the standard operation speed) to the voltage controlledoscillator 151. The voltage controlled oscillator 151 is driven by thephase error signal IG. That is, an oscillation frequency of the voltagecontrolled oscillator 151 is controlled so that the phase of the clocksignal CN outputted from the divider 152 agrees with the phase of theclock signal CK′.

After the modulating clock signal MCK outputted from the voltagecontrolled oscillator 151 having the oscillation frequency thereofcontrolled in this manner is divided into (1/K) by the divider 16, adivided modulating clock signal MCK′ is supplied as a reference clocksignal for modulation to the EFM modulation unit 14 (see FIG. 7).

As described above, the modulation clock generation circuit 15 controlsthe frequency of the modulating clock signal MCK outputted to the EFMmodulation unit 14 via the divider 16 in accordance with the controlsignal SB supplied from the control unit 20 shown in FIG. 7. In otherwords, in the optical disk recording apparatus 100, the frequency of thereference clock signal for modulation supplied to the EFM modulationunit 14 is set under the control of the control unit 20 based on therecording data amount M to be recorded and the recording disk capacityN. Additionally, details concerning the dividing ratio and the like ofthe divider 152 set by the control signal SB will be described later.

The EFM modulation unit 14 subjects the data to be recorded suppliedfrom the host computer (not shown) to EFM modulation using themodulating clock signal MCK′ supplied from the modulation clockgeneration circuit 15 via the divider 16 as a reference clock (so-called1T clock), and outputs an EFM-modulated signal to the recording strategycircuit 13.

The recording strategy circuit 13 subjects the EFM signal supplied fromthe EFM modulation unit 14 to a time axis correction processing and thelike, and outputs the signal to a laser driver (not shown). The laserdriver drives the laser diode of the optical pickup 12, and the CD-R 101is irradiated with the laser beam corresponding to the data to berecorded supplied from the host computer.

As described above, in the optical disk recording apparatus 100, thespindle motor 11 for driving the CD-R 101 is controlled so as to rotatethe CD-R 101 at the speed following the rated linear velocity similar tothat in a conventional recording apparatus. On the other hand, thereference clock for use in the EFM modulation by the EFM modulation unit14 is changed in accordance with the relation between the recording dataamount M and the disk capacity N, and the effective linear velocity ofthe CD-R 101 or the recording density is changed to an optimum value inaccordance with the relation between the disk capacity N and therecording data amount M as illustrated in the above-described threecases.

C. Concrete Example

As described above, in the optical disk recording apparatus 100, thelinear velocity is appropriately changed in accordance with therelationship between the disk capacity N and the recording data amount Mfor the recording. To change the linear velocity in this manner, thecontrol unit 20 controls and sets the dividing ratio (1/B) of thedivider 152 of the phase comparator 150 in accordance with therelationship between the disk capacity N and the recording data amountM. In the following, the above-described three cases, that is, therecording data amounts M of about 650 MB (Case 1), about 670 MB (Case2), and about 540 MB (Case 3), and the recording data amount M of 500 MB(Case 4) are used as examples, while the CD-R set in the optical diskrecording apparatus has a nominal disk capacity N of about 650 MB (ratedlinear velocity of 1.2 m/s). These examples are described using concretenumeric values.

(Case 1) Recording Data Amount M=650 MB

When the recording data amount M is 650 MB, that is, when the diskcapacity N meets the recording data amount M, similar to a conventionaloptical disk recording apparatus, the recording is performed at thelinear velocity identical to the rated linear velocity (1.2 m/s) of theCD-R as the recording object.

Here, the modulating clock signal MCK′ and the dividing ratio of thedivider 152 will be described in a case where the recording is performedwith respect to the CD-R 101 (disk capacity N=650 MB) having the ratedlinear velocity=1.2 m/s at the rated linear velocity of 1.2 m/s withreference to FIG. 9 and FIG. 8 described above. Additionally, in thefollowing description, the numeric values for setting the frequency anddividing ratio will be described in the case where the recording speedis set to the standard operation speed (basic speed). When the recordingis performed at the multiple speeds such as the double speed andfour-fold speed, the respective numeric values are proportional to themultiple speed.

When the recording is performed at the rated linear velocity of 1.2 m/sas the standard operation speed, the frequency of the modulating clocksignal MCK′ for use in the modulation of the EFM modulation unit 14 is4.3218 MHz, and the frequency of the clock signal CK′ is 6.3 kHz.Moreover, when the oscillation frequency of the voltage controlledoscillator 151 is 276.5952 MHz, value B=43904, and K=64 of the dividingratio (1/K) of the divider 16. That is, in Case 1, the oscillationfrequency of the voltage controlled oscillator 151 is divided into1/43904 by the divider 152. As a result, similar to the conventionaloptical disk recording apparatus, the clock signal MCK′ of 4.3218 MHz issupplied to the EFM modulation unit 14. Therefore, in Case 1, thecontrol unit 20 outputs the control signal SB such that the dividingratio of the divider 152 is set to 1/43904.

(Case 2) Recording Data Amount M=670 MB

When the recording data amount M is 670 MB, the recording information isrecorded at the effective linear velocity of about 1.16 m/s as describedabove, and therefore the modulating clock signal MCK′ supplied to theEFM modulation unit 14 has a frequency of 4.3218×670/650=4.4548 MHz.Therefore, the frequency of the modulating clock signal MCK oscillatedfrom the voltage controlled oscillator 151 is 4.4548×64 (K)=285.1058MHz. As a result, the value B for use in setting the dividing ratio ofthe divider 152 is 285.1058 MHz/6.3 kHz=45255. Therefore, in Case 2, thecontrol unit 20 outputs the control signal SB such that the dividingratio of the divider 152 is set to 1/45255.

(Case 3) Recording Data Amount M=540 MB

When the recording data amount M is 540 MB, the recording is performedat the effective linear velocity of about 1.4 m/s as described above,and the modulating clock signal MCK′ supplied to the EFM modulation unit14 has a frequency of 4.3218×1.2/1.4=3.7044 MHz. Therefore, thefrequency of the modulating clock signal MCK oscillated from the voltagecontrolled oscillator 151 is 3.7044×64 (K)=237.0816 MHz. As a result,the value B for use in setting the dividing ratio of the divider 152 is237.0816 MHz/6.3 kHz=37632. Therefore, in Case 2, the control unit 20outputs the control signal SB such that the dividing ratio of thedivider 152 is set to 1/37632.

(Case 4) Recording Data Amount M=500 MB

When the recording data amount M is 500 MB, similar to that in Case 3described above, the linear velocity is set to be higher than the ratedlinear velocity (1.2 m/s) and the recording is performed a determinedlinear velocity of 1.2×650/500=1.56 m/s. Therefore, as in Case 2 or Case3 described above, where a linear velocity other than the rated linearvelocity is used, the linear velocity may be set to 1.56 m/s in order toperform the recording. However, it is stipulated in the existing CDstandard (Red Book) that the recording be performed at a linear velocityof 1.4 m/s or less. Accordingly, in the optical disk recording apparatus100, when the linear velocity determined as described above is higherthan 1.4 m/s, the linear velocity is set to 1.4 m/s and the recording isperformed. Therefore, the value B for setting the dividing ratio of thedivider 152 is identical to the value (37632) of Case 3 described above,and the control unit 20 outputs the control signal SB such that thedividing ratio of the divider 152 is set to 1/37632.

The control unit 20 in the optical disk recording apparatus 100generates the control signal SB for setting the dividing ratio of thedivider 152 from the relationship between the disk capacity N and therecording data amount M as described above. When the control signal SBis outputted and the dividing ratio of the divider 152 is set, and whenthe recording data amount M is larger than the disk capacity N, all therecording data can be compressed and filled in the CD-R. On the otherhand, when the recording data amount M is smaller than the disk capacityN, the extra region of the disk capacity N is used, such that recordingwith a higher quality level is possible by expanding the data andfilling the tracks. Therefore, according to the optical disk recordingapparatus 100, the data can be recorded at the optimum linear velocityin accordance with the relation between the disk capacity N and therecording data amount M without being limited by the rated linearvelocity of the disk.

D. Modification Examples

Additionally, the present invention is not limited to theabove-described embodiments, and can variously be modified asillustrated hereinafter.

Modification Example 1

In the above-described embodiment, the recording is basically performedat a linear velocity determined by L×N/M, assuming that the diskcapacity is N, the recording data amount is M, and the rated linearvelocity of the disk is L. However, when it is possible to select anyone of a plurality of values of linear velocities (e.g., three valuessuch as 1.16 m/s, 1.2 m/s, and 1.4 m/s) beforehand and perform therecording, the tentative linear velocity LT obtained by theabove-described L×N/M is used as a reference, the closest linearvelocity is selected, and the recording may be performed at the selectedlinear velocity.

Additionally, in the above equation, N/M is used, although M/N isrecited in the claims. This is because a large value of the “linearvelocity” used in the specification corresponds to a small value of the“recording density” (recited in the claims). Therefore, when the“recording density” is used as the unit instead of the “linearvelocity”, the above equation is represented as LT=L×M/N.

When the method of selecting the optimum linear velocity from theplurality of linear velocities as described above is used, a table shownin FIG. 10 may be stored in the ROM of the control unit 20 of theoptical disk recording apparatus 100. As shown, in the table, a range ofvalues which can be taken by the disk capacity N/recording data amountM, and the values B for setting the dividing ratio of the divider 152are associated with each other and stored in the memory. Moreover, N/Mis computed from the disk capacity N and recording data amount Mobtained by the control unit 20, and the value B associated with therange which agrees with the value of the N/M is selected.

For example, when the disk capacity N is 650 MB, and the recording dataamount M is 670 MB, N/M is less than 1.0, B=45292 is therefore selected,and the dividing ratio of the divider 152 is set to 1/45292 (the same asCase 2). Therefore, similar to Case 2 described above, the recording isperformed at the linear velocity of about 1.16 m/s. Moreover, when thedisk capacity N=650 MB, and the recording data amount M=540 MB, N/M isgreater than 1.18, B=37632 is therefore selected, and the dividing ratioof the divider 152 is set to 1/37632 (the same as Case 3). Therefore,similar to Case 3 described above, the recording is performed at thelinear velocity of 1.4 m/s.

Modification Example 2

Moreover, in the above-described embodiment, the optical disk recordingapparatus 100 controls the spindle motor 11 to drive the CD-R 101 at thespeed following the rated linear velocity similar to that in aconventional recording apparatus. On the other hand, when the referenceclock for use in the EFM modulation is changed, the linear velocity(recording density) is effectively changed. The invention is not limitedto this example, and the method may include: using the signal of thefrequency following the rated linear velocity in the reference clock foruse in the EFM modulation by the EFM modulation unit 14 (the same as ina conventional recording apparatus), and rotating the CD-R 101 at avariable speed different from the rated linear velocity of the CD-R 101,so that the linear velocity may be changed.

When the CD-R 101 is rotated and driven at a speed that is differentfrom the rated linear velocity of the CD-R 101 as described above, thecontrol unit (driving control means) 20 may control the spindlecontroller 19 in accordance with the relationship between the diskcapacity N and the recording data amount M. Here, FIG. 11 shows theconstitution of the spindle controller 19. As shown in the drawing, thespindle controller 19 has a phase comparator 191 and divider 192. Thedividing ratio of the divider 192 is set by a control signal SB′supplied from the control unit 20, and the clock signal CK supplied fromthe crystal oscillator 21 is divided at the set dividing ratio. Thedivided clock signal CK″ is inputted into one input end of the phasecomparator 191.

The bi-phase clock BC supplied from the ATIP demodulation unit 18 isinputted into the other input end of the phase comparator 191. The phasecomparator 191 outputs an error signal to the motor driver (not shown)in accordance with the phase difference of both inputs, and the motordriver drives the spindle motor 11 in accordance with the error signal.That is, when the dividing ratio of the divider 192 is changed, therotational velocity of the CD-R 101 by the spindle motor 11 can bechanged. Therefore, when the control unit 20 outputs the control signalSB′ for rotating and driving the CD-R 101 so as to perform the recordingat the linear velocity in accordance with the relationship between thedisk capacity N and the recording data amount M, similarly as theabove-described optical disk recording apparatus 100, the recording canbe performed at the optimum linear velocity in accordance with therelationship between the disk capacity N and the recording data amountM.

Modification Example

Additionally, in the optical disk recording apparatus 100, the CPU ofthe control unit 20 executes a recording process including a processingfor setting the linear velocity in accordance with the relationshipbetween the disk capacity N and the recording data amount M according tothe program stored beforehand in the ROM, but a control circuitconstituted by a dedicated hardware may perform the process similarly asdescribed above. Moreover, various recording mediums such as a CD-ROMand floppy disk in which the program for allowing a computer to realizethe above-described processing may be presented to the user, or theprogram may be presented to the user via transmission mediums such asthe Internet. For example, the program for performing the processinginstalled in an electrically erasable and programmable ROM (EEPROM) ofthe conventional optical disk recording apparatus via the recordingmedium or the transmission medium may be updated so that the processingsimilar to that of the above-described optical disk recording apparatus100 is performed.

As described above, according to the present invention, an optimumrecording can be performed in accordance with a volume of data to berecorded and a capacity recordable in an optical disk.

1. A method of recording contents information along a track of anoptical disk of a writeable type and having a pre-determined recordingdensity, said method comprising: detecting an actual volume of thecontents information to be recorded into the optical disk; detecting anominal capacity of the optical disk, said nominal capacity beingindicative of a rated volume of information to be recorded at maximum;calculating an adjusted recording density LT of the contents informationbased on the detected actual volume and the detected nominal capacity;and recording the contents information into the optical disk at theadjusted recording density such that the actual volume of the contentsinformation can fit into the nominal capacity of the optical disk,wherein the adjusted recording density is calculated according to theequation LT=L×M/N, where M denotes the actual volume, N denotes thenominal capacity, and L denotes the pre-determined recording density. 2.The method according to claim 1, wherein the optical disk ispre-recorded with index information indicating progression of positionor time along the track at said pre-determined recording density.
 3. Themethod according to claim 1, wherein the adjusted recording density iscalculated when the actual volume is greater than the nominal capacityof the disk.
 4. The method according to claim 1, wherein, when thecalculated value of the adjusted recording density is lower than alower-limit value, the value of the adjusted recording density is set tobe equal to said lower-limit value.
 5. The method according to claim 1,wherein the optical disk is a CD-R or a CD-RW formed according to astandard of the Orange Book, and the nominal capacity of the opticaldisk is detected based on the last possible start position of a lead-outarea in the ATIP time code pre-recorded in the optical disk.
 6. Amachine-readable medium for use in a machine having a CPU, the mediumcontaining program instructions executable by the CPU to cause themachine to perform a process of recording contents information along atrack of an optical disk of a writeable type, said optical disk having apre-determined recording density, and said process comprising: detectingan actual volume of the contents information to be recorded into theoptical disk; detecting a nominal capacity of the optical disk, saidnominal capacity being indicative of a rated volume of information to berecorded at maximum; calculating an adjusted recording density LT of thecontents information based on the detected actual volume and thedetected nominal capacity; and recording the contents information intothe optical disk at the adjusted recording density such that the actualvolume of the contents information can fit into the nominal capacity ofthe optical disk, wherein the adjusted recording density is calculatedaccording to the equation LT=L×M/N, where M denotes the actual volume, Ndenotes the nominal capacity, and L denotes the pre-determined recordingdensity.
 7. The machine-readable medium according to claim 6, wherein,when the calculated value of the adjusted recording density is lowerthan a lower-limit value, the value of the adjusted recording density isset to be equal to said lower-limit value.
 8. A method of determining anadjusted recording density for an optical disk of a pre-determinedformat, said method comprising: detecting a first data amount N from theoptical disk, wherein the first data amount is determined based on atrack length TR and a recording density L under the pre-determinedformat, said track length being the length of the disk's track which isrecordable under the pre-determined format, and said recording densitybeing represented by a signal that is pre-recorded in the track;detecting a second data amount M, said second data amount representingthe amount of data to be recorded into the optical disk; and calculatingan adjusted recording density LT according to the equation LT=L×M/N suchthat the second data amount is recordable into said track of length TRat the adjusted recording density, wherein M is not equal to N.
 9. Amethod of determining an adjusted recording density for an optical diskof a pre-determined format, said method comprising: detecting a firstdata amount N from the optical disk, wherein the first data amount isdetermined based on a track length TR and a recording density L underthe pre-determined format, said track length being the length of thedisk's track which is recordable under the pre-determined format, andsaid recording density being represented by a signal that ispre-recorded in the track; detecting a second data amount M, said seconddata amount representing the amount of data to be recorded into theoptical disk under the pre-determined format; and calculating anadjusted recording density LT according to the equation LT=L×M/N suchthat the second data amount is recordable into said track of length TRat the adjusted recording density under the pre-determined format,wherein, when the calculated value of the adjusted recording density islower than the lowest value of a specified range of recording densitiesfor recording data into the disk, the value of the adjusted recordingdensity is set to be equal to said lowest value of said range.
 10. Amachine readable medium containing program instructions that whenexecuted cause a machine to perform a process of determining an adjustedrecording density for an optical disk of a pre-determined format, saidprocess comprising: detecting a first data amount N from the opticaldisk, wherein the first data amount is determined based on a tracklength TR and a recording density L under the pre-determined format,said track length being the length of the disk's track which isrecordable under the pre-determined format, and said recording densitybeing represented by a signal that is pre-recorded in the track;detecting a second data amount M, said second data amount representingthe amount of data to be recorded into the optical disk; and calculatingan adjusted recording density LT according to the equation LT=L×M/N suchthat the second data amount is recordable into said track of length TRat the adjusted recording density, wherein M is not equal to N.
 11. Amachine readable medium containing program instructions that whenexecuted cause a machine to perform a process of determining an adjustedrecording density for an optical disk of a pre-determined format, saidprocess comprising: detecting a first data amount N from the opticaldisk, wherein the first data amount is determined based on a tracklength TR and a recording density L under the pre-determined format,said track length being the length of the disk's track which isrecordable under the pre-determined format, and said recording densitybeing represented by a signal that is pre-recorded in the track;detecting a second data amount M, said second data amount representingthe amount of data to be recorded into the optical disk under thepre-determined format; and calculating an adjusted recording density LTaccording to the equation LT=L×M/N such that the second data amount isrecordable into said track of length TR at the adjusted recordingdensity under the pre-determined format, wherein, when the calculatedvalue of the adjusted recording density is lower than the lowest valueof a specified range of recording densities for recording data into thedisk, the value of the adjusted recording density is set to be equal tosaid lowest value of said range.